As someone who has gone through tests and been diagnosed with ADD, I think I understand the frustrations, and it definitely does not "feel" normal.
Not being able to hold onto a thought for more than 3 minutes, or having to deal with potentially being distracted by every little thing that happens around me does not feel like the normal state of affairs. Trivial tasks can take me hours instead of minutes in some situations.
Unfortunately I'm currently in a country that doesn't allow me to get medication for this (and previously I was in a country that believes that ADD/ADHD magically disappears when you turn 18), but I still have good memories of how much it helped me get through middle school and high school (I went from almost never finishing my math homework to being able to finish everything in class in only half the allotted time).
For sure - there is a wide variety of human experience, and each of us understands our own. By understanding ADHD, I was talking about the causes and the nature, not the experience.
If drugs are the only way someone like you can lead a happy life, then you should be able to use them.
Normal vision could be interpreted as a range much larger than our arbitrary standard of "perfect", 20/20 vision.